Method of decolorizing liquids



July 2, 1940. E. G. STEELE 2,206,337

, vMETHOD OF DECOLORIZING LIQUIDS Filed-Feb. 1o. lase l 3mm/rw ifdwpl Goodwpz siecle, K

Passes July 2, 1940 PATENT oFFl-CE l-METHQD 0F DECOLOBIZING LIQUIDS Edwin c. steels, nanas, Tex.; may suele executrix oi said Edwin (3i.y Steele, deceased Application February 10, 1938, Serial No. 189,894.

1 scmms. (ci. lss-147) This invention' or discovery relates to purifica- A grain size frequently used for decolorizing oil tion of liquids: and it comprises a method of utilizing a mass of granular adsorbent material, such as` fullers earth, in a cyclic and economical manner, in decolorizing and like treatments Aof liquids, and especially oils, `whereirrsuch a mass of adsorbent material is contacted with a liquid containing coloring matter or other impurities which are takenup by the adsorbent, and the used adsorbent is then freed of residual liquid and reviviiied by heating to a temperature sufil ciently high to burn out adsorbed organic matter but insufllcientto eiect. substantial lessening of its adsorbent power, and wherein the mass of reviviiled adsorbent is classified into at least two portions, usually including a major portion having higher adsorbent power than the unseparated mass and a minor portion having lower adsorbent power than the unseparated mass, and wherein the said minor portion is withdrawn from the `system and the major portion is combined with a further quantity of material having equal or higher adsorbent power `to reconstitute thel mass, which is then returned to the system` for contact with a further quantity of liquid, whereby the adsorbent power of the granular material employed is maintained substantially uniform throughout repeated cycles of use; and it comprises classification of the used and reviviled granular adsorbent by a treatment on a classifying table which is advantageously combined with removal of undesirably fine particles and dust; all as more fully hereinafter set forth and claimed.

Granular adsorbent materials, and especially fullers earth and like adsorbents of a mineral nature, are widely used for decolorizing and like treatments of various liquids. Oils, and especially mineral` oils and derivatives or fractions thereof, sometimes designated petroleum products, are treated with such adsorbents on a very large scale. The treatment is frequently e'ected by percolating the oil, etc., through a suitable bed or mass of the granular adsorbent material. Sometimes the adsorbent is stirred into the liquid and then separated out, f. as by ltration, after sulllcient contact. In that case, the particles or grains of adsorbent employed aregenerally ner than when the percolation method .is followed.

Even with the percolation method, however,`

the size of the grains or granules of adsorbent may vary considerably; from a size which will not pass through a screen having meshes per inch `to asize which willfjust pass` through a 'screen having 15 meshes per inch, for example.

contains granules ranging in size from 15 to 30 mesh. My invention is not limited to the use of particles or granules of this particular size, how ever.`

After the oil or other liquid has been decolorized or otherwisepurifled by contact with granular fullers earth, for example, the adsorbent is usually `washed with an appropriate solvent to eliminate the remaining liquid. The solvent is 10 then withdrawn, and the material is fitted for re-use as a decolorizing agent, by reviviilcation. This includes re-burning in a suitable kiln or furnace, at a temperature high enough to burn v out residual organic matter. Suitable apparatus l5 for revivifying includes Wedge furnaces, vertical tumbling kilns, and revolving-cylindrical kilns mounted at a slight angle to the horizontal. The earthy decolorizing agents are generally rvivifled in an oxidizing atmosphere.

The decolorizing agents employed in the processes of this nature are ordinarily re-burned and re-used many times. For example, fullers earth may be used anywhere up to 10 to 50 times for decolorizing various mineral oils, if it is suitably 25 revivifled after each use. This repeated use and revivification' gradually reduces the adsorbent or decolorizing value. This reduction occurs more rapidly with fuller's earth than with bonechar. for example, but in masses of either ma- 30 terial different granules degrade at different rates. It appears that through repeated use and revivication, the pores of the material become closed or lled up, and I have found that the density of a material `such as fullers earth is 35 indicative of its decolorizing value.` `.I believe that this may be explained as follows.

Fullers earth is a commercial name for any clay of suillcient adsorptive power to render its use worth while in reilning oils, including min- 40 eral oil as well as vegetable and animal oils. In

- reilning, the function of the clay is to adsorb coloring matter or some other non-oily constituent of the oil, and to collect dispersed solids and liquids of colloidal flneness. In the case of mineral oils, 45

a marketable product may be clayed several times during the routine oiipr'oducion.l 'I'he technical value of any clay or fullers earth is proportional `to its surface, interior and exterior. Other things below the sintering point of the clay, to eliminate organic matter and carbon as completely as possible. However, in practice the temperature can seldom be controlled with suilicient -accuracy to prevent a certain amount' of sintering; shrinkage of some of the clay during this re-burning seems to be inevitable. This shrinkage is at the expense of internal porosity; and internal voids, some of which are probablyof almost molecular dimensions, are obliterated. Any quantity of re-burned fullers earth normally contains a large portion of granules or particles which still .retain substantially their original effectiveness, and also contains a minor 1l proportion of granules shrunk suiiiciently to reduce their decolorlzing action to a point where it is not useful. Each re-burning of the mass adds to the quantity of shrunken granules which, of course, have higher density than the effective material. As a result, the total adsorbent power frequently continued until more than two-thirds of the entire batch was inert and useless before the batch was discarded. One result of this has been that decolorizing material was frequently in use in which only one-third of the total vmass` was material having any substantial decolorlzing value. However, even if the mass was discarded at this stage of degradation, the user was discarding a ton of useful decolorizing agent with each two tons of useless material.

Because of this, it has frequently been the practice to store quantities of decolorizing agent in various degrees of degradation, and lto employ the poorest available material which would satisfy the requirement o f a particular treatment. With this practice, when a high degree of decolorization was required,'it was sometimes neces- 5 sary to delay a batch of liquid until a sufficiently good batch of decolorlzlng agent was available. On the other hand, if a high degree of decolorization was not necessary, economy often required that the oil, for'example, was available a vbatch of decolorizing agent which was the poorest which would sumce for the 'particular job. In additionto the inconvenience of this method of operation, it has entailed high n investmentV cost in decolorizing agent'and in buildings, bins and tanks for holding and using a large number of separate batches of material, and a correspondingly high' operating cost.

I have found that the dimculties and undesir- 'dable necessities of'pest methods of operating oil decolorizing and similar processes can be over- .someif the adsorbent is subjected, after useand reviviflcation, to a grading or separation which eliminates that portion of 'the materialhaving 7o no useful decolorizing value. This classification can be controlled to eliminate material having less than any predetermined decolorizing value, 'or to separate the revivlned material into classes having decolorlzlng values graded, in any prezt selected number of steps. from substantially no be delayed until there @motionv of the table granules most enectively when air is simultanevalue to substantially the value of fresh material.

I `have further found that the separation or grading or classincation Arequired for this stage of my process is most effectively accomplished by the use of a classifying table similar' to the type of table used heretofore for the classification of other materials. Such a table and its other object achieved bymy invention .is the provision of a process of decolorizing mineral oil and the like, during oil refining operations, for example, in which fullers earth or a similar granular earthy decolorizing material is employed to decolorize the' oil, is freed from residual olland revivifled, and is then separated into at least two portions, one of .which has better decolorizing value than the unseparated material. Simultaneously, if desired, portions may be separated having intermediate decolorizlng value and good sweet'ening value, as that term is used in oil refining.

An advantage of my process is that it may readily be operated in such a manner as to remove from the reviviiled material any powdered or undersized material, regardless of decolorizing value. The filtering capacity or flow rate of the remaining material is thereby maintained at a higher level. Other objects and advantages of my invention will be apparent from the following description and the appended claims.

As previously indicated, the decolorizing value of granular adsorbents, and particularly of fullers earth and like earthy decolorizing agents which have been used and revivifled, is quite directly related to the density of the material. However, due to the physical'nature of this material itis not convenient or economical to separate it into fractions of varying decolorizing value by air flotation and similar air separation methods, in which it is attempted to suspend the wh'ole mass of material in air. Such processes find utility in the removal of fines, dust and decomposed portions of the granular material, but

`are not commerciallypracticable forthe classi'- flcation of material of the desired size in accordance with decolorizing value.

I have found, however, that'the desired classiiication may be obtained by the use of a suitable classifying table. Such a table preferably has a top or deck which is permeable to air. but not to the granules being p thereon, and this 'deck is advantageously provided with a plurality of parallel rimes extending from'one .end of the Atable to a point somewhat short of the opposite end of the table. In operation, this table ls reciprocated endwise, advantsgeoiuly with a simule taneous upward thrust or motion, which issometimescalleda" motion This ects classification `of the ously passed upwardly throughthe deck. The

' granular decolorixing material to be classiiied is supplied in a stresmfto one corner of the table,

and any desired numberV of separated portions or -clauses are dischargedfrom a sone extendingascesa? along the opposite side or opposite end of the table. f i The revivifled fullers earth generally contains la certain small amount of undesirably fine mate` pose of lifting undesirably fine material out of the mass of larger granules, and it may then be carried oil.' through a suitable hood connected by a duct tothe intake of an exhaust fan or blower, for example; If desired, this fine material may be recovered in a cyclone separator or the like,

and may be thereafter employed or disposed of, as desired. l

One form of apparatus suitable for effecting the separating or classifying step of my process is shown in the accompanying drawing, in which Fig. 1 is a'plan view of a suitable separating or classifying table with associated mechanism, and Fig. 2 is an elevational view, with parts broken away, of the same apparatus.

In the drawing, the deck of the table is indicated at I. A stream of dry particles of an adsorbent, such as revivied -granular fuller's earth, is fed onto the deck of the table at a rear corner from a feed hopper 5. When the table is reciprocated the granules travel across the deck, and individual particles take different paths in accordance `with their decolorizing power and density. The streams of particies so separated,

, reciprocating motion upon rotation of the shaft discharge over an edge l of the deck into a pluralityof receivers such as funnels 33, `34, 35, 36, 31, I8 and 39.

The deck I advantageously has a slight down-` ward tilt transversely, from the point of feed at the rear to the front or discharge edge 1, and has a slight upward tilt longitudinally from the feed end to the opposite end. The table'is supported on pivoted legs 9, which extend from base members I0 to table lugs Il or other suitable means of attachment. By means of eccentrics `I2 and rods I3, the table is given a longitudinally l5 on which the eccentrics are mounted.

The pivoted legs 9 are preferably positioned at an angie to the vertical, as shown, so that the motion longitudinally imparted `by the rods Il is accompanied by an arcuate upward thrust of the table. This is sometimes designated a grasshopper motion.

1The shaft I5 is joumaled in suitable4 supports i4, and power for rotating the shaft is supplied from a motor (not shown) through a belt 2 toa shaftV III having a conepulley i6 mounted thereon. This pulley I8` is connected by aA belt -Il to a cone pulley I8 on theshaft l5. Other suitable' driving means may be substituted if desired. A belt shifting device may be used with the ap*- paratus illustrated to controlthe frequency of reciprocation of the table. and such a device is conventionally illustrated at 4l.

The deck ofl the table is advantageously al perforate sheet on which the granular material is separated. This perforate sheet may be a me- `tallic fabric or a perforated plateor any similar strong porous material.v Itl must be sufficiently `the discharge side. For example, the .maximum .pass algreater amount of air through the deck through the material where it first comes .onto

open to' permit' passage of air, but the perforation`s mustbe small enough to prevent the passage of granules of the decolorizing material therethrough. An upward passage ofair through the perforate deck is essential to the most elcient operation of this type of .classifying table.,

An air chest 20 is positioned immediatelybelow the deck with the perforate sheet or deck forming the'top wall of the chest. A blower 22 supplies air to the chest through a suitable duct 2|, at a moderate pressure. The volume of air may be controlled by regulator 23 or the like in duct 2l. It is also advantageous to provide the -interior of the chest with slats or bailles, indicated `at I2 and 43, to effect the desired distribution of the air to the deck surface.

It is advantageous to provide the deck sur.- face with a number of riilles 8 extending lengthwise of the table, as the provision of such rimes reduces-the table size required for the separation of a given quantity of material. These'riiiles preferably have a height of about one-fourth to one-half inch at the feed end of the table and gradually diminish in height ltoward the opposite end of the table. Advantageously, they terminate a few inches short ofthe end opposite from the point of feed. I sometimes find it desirable to increase the height of the individual rillies from the feed side of the table transverselytoward height of successive rillles proceeding. fromthe feed side to the discharge sideof the table may increase from one-quarter inch to three-eighths inch, or from one-eighth inch to one-half inch, i depending upon the maximum size of the particles undergoing separation.` These riffles are conveniently constructed with a right-angle crosssection, which provides a horizontal ange for fastening to the deck and a vertical flange or face which is the effective rifile.

The mass of granular materialy undergoing separation naturally tends to :form a,much thicker layer at the `feed end of the table than at the opposite end. For this reason, it is desirable to Y at the feed end thanat the opposite or discharge end. This result may be accomplished by means of bailles of suitable shape and form which are conveniently fastened to the lower side of the deck, inside the air chest. These` bailles may an conveniently be tapered, with the widest portion at the discharge end ofthe table and the narrowest portion at the feedend so that more air is permitted to pass through there.

Another effect of the maximum blast of air 4when it is first fed onto the classifying table,

the une materiai is uned out or the mass and 05 can then be readily picked up and carried oil' through a collecting hood 2l, a duct 29', and. a blower 30, to a cyclone separator Il, and a container 32,' or other suitable point of disposal.

separated in this way and collected in the container 32, is suitable for use .in thev contact process of decolorization. l

i In the practice of my separating or classifying Fine clay or fuller's earth, for example, which is 70 step. the table is setin motion and the air supply to the-chest under the perfor-ate deck is turned on. Forv best results, the exhaust ian or blower connected to the hood 23 is also started in operation. The dry granular fullers earth or other decolorizing agent, which ordinarily has justpreviously been revivied, is fed to the table through the feed hopper 5. The combination ofthe reciprocating of grasshopper motioncf the decirl with the upward flow of the air through the deck,

causes the particles to travel across the table from the point oi? their introduction. In the course of this travel, the individual particles take .different courses, depending on their physical characteristics, and they are eventually discharged over different portions of the dischargecharges into the funnel 33, for example. The

granules discharged from successive zones around the discharge edge of the table, starting with funnel 33, have successively diminishing decolorizing values. For example, it is not uncommon to obtain at the last zone (funnel 39 in the drawing) material which has traveled almost entirely longitudinally on the table, and which has substantially no decolorizing value.

As an example 4of the operation of this classifying procedure, I separated by the process and apparatus above-described, a quantity of used and re-burned fullers earth from an oil refinery. Several identical samples of light petroleum lubricating oil were percolated through batches of separated clay from various discharge funnels, with the results shown below:

Color of oil before percolation through clay-- 74 Color of oil. percolated through unseparated clay f Color of oil percolated through separated clay from tunnels 33, 34 and 35 v 9 Color of oil percolated through separ-ated clay from tunnels 36 and 31 36 Color of oil percolated through separated clay from funnels 38 and 39 65 `The conditions of each percolation or filtering test were, of course, maintained uniform, to secure comparability. All colors were determinedv a on a Lovibond colorimeter, using a one inch oil cell and standard color glasses of the 500 amber series.

For another specific example, the colors of oil percolated through an unseparated clay and through various cuts therefrom were as follows:

Unilltered oil- Oil from unseparated clay 33 Oil from clay from funnel 33 14 Oil from clay fromv funnels 34 and 35 27 Oil from clay from funnels 36, 31, 38 and 39-- 59 A large number of different fullers earths were subjected-to similar separation and'similar determination of decolorizing value, and the results were invariably `of the same nature. My process has likewise been'practiced with bone char, and tests have been made with partly refined sugar solutions and other liquids. The tests have invariably shown that the dry granular decolorizing mediums subjected to my process show substantially varying decolorizing value according to the portion of thel separating table from which they discharge.

re-burned 9 or 1 0times.

By maintaining a strong exhaust draft above the `decl: l in the vicinity ofthe feed zone l, through hood' 28 and blower 30, I find it possible to remove undesirably ne materialconcurrently with my separation according to., decolorizing value, and in this manner I attaingthe commercial desideratum of maximum decolorizing effect and maximum rate of filtration. Because of the high investment cost involved in filtering operations, the time required for commercial filtering, and the relatively high loss of liquid in clay soakage, there is a very great advantage' in this process.

The most useful application of my classifying procedure appears to -be in decolorizing processes 'further use is uneconomical,l without losing any material which is of further value. Regardless of the point at which' any particular user considers his decolorizing agent to be of-no further value, my process permits close and continuous separation at that point.

I consider the most advantageous embodiment of my invention to be the continuous separation of the decolorizing mass at some predetermined degree of degradatlonfwith the rejection of all of the inferior material separated and the continuous replacement of the rejected material by material having a decolorizing value which is equal to or betterl than the average of that retained from the separation. ,This general procedure has been. employed, in various industries, but the `advantages of it are perhaps best illustrated in connection with the use of fullers earth for decolorizing petroleum products. For example, in one refinery in which petroleum oils are treated, it was customary to discard all of the decolorizing clay'after it had been used and After the adoption of my process, this same refinery was able to separate out and reject a small percentage (around 5 per cent) of depreciated or degraded clay after each burning, replacing that rejected clay with new clay. They thereby maintained a mass of decolorizing agent of substantially uniform decolorlzing value, and'continually characterized by a decolorizing value better than that of similar clay which had been used only once or twice,

heating it to a temperature sufliciently high to burn out adsorbed organic matter, whereby the decolorizing power or some granules of said decolorizing materialis decreased, classifying. the revlvied granular decolorizing material into at least two portions including a portion characterized by higher decolorizing power than the unseparated material and a second portion characterized by lower decolorizing power than the unseparated material, withdrawing said portion of lower decolorizing power, adding to said portion of higher decolorizlng power a suilicient urther quantity of granular decolorizing material having at least equally high decolorizing power to make up the desired total mass of decolorizing material,-and contacting the resulting mass of decolorizing material with a further quantity of said liquid to remove coloring matter therefrom. 2. The method of claim 1, wherein the liquid is a petroleum product.

.perature suiiciently elevated to burn out adsorbed organic matter, whereby the density of some granules ofthe iullers earth is increased, classifying the revivined granular fullers earth into at least two portions including 'a portion characterized by higher adsorbent power than the unseparated `material and a second portion characterized by lower adsorbent power than the unseparated material, withdrawing said portion oi' lower adsorbent power, adding to said portion of higher adsorbent power a suilicient further quantity of granular adsorbent fuliers earth having at least equally high adsorbent power` to malle up the desired totalmass of adsorbent. and contacting the resulting mass of fullers earth with af further quantity of said'oil to adsorb matter therefrom. l

5. The method of claim 4. wherein the oil is a petroleum product.

6. 'I'he method of claim 4, wherein the adsorbed matter is Vcoloring matter.

7. 'I'he method of claim 4, wherein the revivied granularfullers earth is classified by charging it in a stream onto a supporting means comprising a' plane so disposed that particles resting loosely thereon will be drawn in one direction by the `force of gravity, and then subjecting the granular fuller's earth to a force tending to cause individual granules to travel on the plane in a direction other than that resulting from the force otgravity.

8. The method of claim 4, wherein the revivified' granular fullers earth is classified by charging it in a stream onto a perforate inclined plane and there subjecting Vit simultaneously to a force tending `to cause individual granules to travel on the plane in al direction other than that resulting from the force oi' gravity and to a blast o1' air from below having sufficient strengthg to lift out oi the material particles of undesired 

